This thesis is about whether language affects thinking. It deals with the linguistic relativity hypothesis, which proposes that the language we speak influences the way we think. This hypothesis is investigated in the domain of caused motion (e.g., ‘The man rolled the tyre into the garage’), by looking at Spanish and Swedish, two languages that show striking differences in how motion events are encoded. The thesis consists of four studies. The first two focus on native speakers of Spanish and Swedish. Study I compares how Spanish and Swedish speakers describe the same set of caused motion events, directing the spotlight at how variable the descriptions are in each language. The results confirm earlier findings from semantic typology regarding the dominant ways of expressing the events in each language: Spanish behaves like a verb-framed language and Swedish like a satellite-framed language (Talmy, 2000). Going beyond previous findings, the study demonstrates—using the tools of entropy and Monte Carlo simulations—that there is markedly more variability in Spanish than in Swedish descriptions. Study II tests whether differences in how Spanish and Swedish speakers describe caused motion events are reflected in how they think about such events. Using a novel similarity arrangement task, it is found that Spanish and Swedish speakers partly differ in how they represent caused motion events if they can access language during the task. However, the differences disappear when the possibility to use language is momentarily blocked by an interference task. The last two studies focus on Swedish learners of Spanish as a second language (L2). Study III explores how Swedish learners (compared to native Spanish speakers) adapt their Spanish motion descriptions to recently encountered input. Using insights from the literature on structural priming, we find that Swedish learners initially expect to encounter in their L2, Spanish, those verb types that are typical in Swedish (manner verbs like ‘roll’) but that, with increasing proficiency, their expectations become increasingly attuned to the typical Spanish pattern of using path verbs (like ‘enter’).  These expectations are reflected in the way L2 learners adapt their own production to the Spanish input. Study IV asks whether recent linguistic experience in an L2 can affect how L2 learners think about motion events. It is found that encountering motion descriptions in the L2 that emphasize different types of information (path or manner) leads L2 speakers to perceive similarity along different dimensions in a subsequent similarity arrangement task. Taken together, the thesis argues that the study of the relation between language and thought affords more valuable insights when not posed as an either-or question (i.e., does language affect thought or not?). In this spirit, the thesis contributes to the wider aim of investigating the conditions under which language does or does not affect thought and explores what the different outcomes tell us about language, thought, and the intricate mechanisms that relate them. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 3: Manuscript.</p>

L'obiettivo del presente lavoro è quello di esaminare criticamente le prospettive teoriche più note sul problema delle relazioni tra sviluppo concettuale del bambino ed acquisizione della prima lingua. Per quanto il lavoro si concentri in particolare sullo sviluppo della componente lessicale, ovvero sul legame tra concetti e apprendimento delle parole con cui gli stessi vengono codificati, verranno necessariamente trattati anche alcuni aspetti relativi alla competenza morfologica e sintattica. Dopo aver presentato sinteticamente le principali teorie proposte nell'ambito della linguistica acquisizionale e della psicologia dello sviluppo, procederemo ad una problematizzazione e discussione dei punti critici delle stesse alla luce dei risultati ottenuti in sede sperimentale negli ultimi anni. Partendo dalla consapevolezza che nell'ambito della linguistica, forse ancor più che in altre discipline, il contrasto tra impostazioni teoriche diverse si traduce spesso in discrepanze significative nell'interpretazione degli stessi dati empirici, abbiamo cercato di dare lo stesso spazio ai vari orientamenti teorici. L'obiettivo di questa tesi, infatti, non è quello di dare giudizi di merito sulla validità di una teoria in quanto tale rispetto ad un'altra, quanto di discutere in modo trasversale i nodi più problematici delle varie teorie e le implicazioni delle stesse. Questo intento è particolarmente evidente nelle conclusioni della tesi, strutturate intorno ad una serie di domande di ricerca. / This work provides a critical overview of the major theoretical perspectives on the relationships between conceptual development and first language acquisition. While our focus is on lexical development (ie. on the relation between learning a word and acquiring the relevant concept), we will also touch on some aspects which pertains more specifically to morphological and syntactical development. After briefly introducing the major theories developed in the field of first language acquisition and developmental psychology, we will discuss them in the light of experimental data collected in recent years. As the same empirical findings tend to be interpreted in completely different ways, in our work we tried to give voice to authors supporting different views. Our goal is not to assess the merits of these theores as such, but to take this comparison as an opportunity to discuss the implications and issues thereof. This will be particularly clear in the Conclusions of our work, which are structured as a series of research questions.